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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <style>
        table {
            width: 800px;
            margin: 100px auto;
            text-align: center;
            border-collapse: collapse;
            font-size: 14px;
        }

        thead tr {
            height: 30px;
            background-color: skyblue;
        }

        tbody tr {
            height: 30px;
        }

        tbody td {
            border-bottom: 1px solid #d7d7d7;
            font-size: 12px;
            color: blue;
        }

        .bg {
            background-color: yellowgreen;
        }
    </style>
    </head>

    <body>
        <table>
            <thead>
                <tr>
                    <th>代码</th>
                    <th>名称</th>
                    <th>最新公布净值</th>
                    <th>累计净值</th>
                    <th>前单位净值</th>
                    <th>净值增长率</th>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <td>003526</td>
                    <td>农银金穗3个月定期开放债券</td>
                    <td>1.075</td>
                    <td>1.079</td>
                    <td>1.074</td>
                    <td>+0.047%</td>
                </tr>
                <tr>
                    <td>003526</td>
                    <td>农银金穗3个月定期开放债券</td>
                    <td>1.075</td>
                    <td>1.079</td>
                    <td>1.074</td>
                    <td>+0.047%</td>
                </tr>
                <tr>
                    <td>003526</td>
                    <td>农银金穗3个月定期开放债券</td>
                    <td>1.075</td>
                    <td>1.079</td>
                    <td>1.074</td>
                    <td>+0.047%</td>
                </tr>
                <tr>
                    <td>003526</td>
                    <td>农银金穗3个月定期开放债券</td>
                    <td>1.075</td>
                    <td>1.079</td>
                    <td>1.074</td>
                    <td>+0.047%</td>
                </tr>
                <tr>
                    <td>003526</td>
                    <td>农银金穗3个月定期开放债券</td>
                    <td>1.075</td>
                    <td>1.079</td>
                    <td>1.074</td>
                    <td>+0.047%</td>
                </tr>
                <tr>
                    <td>003526</td>
                    <td>农银金穗3个月定期开放债券</td>
                    <td>1.075</td>
                    <td>1.079</td>
                    <td>1.074</td>
                    <td>+0.047%</td>
                </tr>
            </tbody>
        </table>
        <script>
            /* 
            需求： 
                 1.鼠标进入tr，tr添加 class bg
                 2.鼠标离开tr， tr的clss清空
            */
            var trs = document.querySelector('tbody').querySelectorAll('tr');
            for (var i = 0; i < trs.length; i++) {
                // 1. 鼠标进入tr，tr 添加class bg
                trs[i].onmouseenter = function () {
                    this.className = 'bg';

                }
                // 2. 鼠标离开tr tr的class清空
                trs[i].onmouseleave = function () {
                    this.className = '';
                }
            }
        </script>
    </body>

</html>